[jira] [Commented] (ZOOKEEPER-2783) follower disconnects and cannot reconnect

["Ben Sherman (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2783?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16035228#comment-16035228 ] 

Ben Sherman commented on ZOOKEEPER-2783:
----------------------------------------

Digging in, i believe this is a problem across the election ports - the connections become stale.  Fix looks like it might be in ZOOKEEPER-1748.

> follower disconnects and cannot reconnect
> -----------------------------------------
>
>                 Key: ZOOKEEPER-2783
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2783
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: leaderElection
>    Affects Versions: 3.4.10
>         Environment: centos 7, AWS EC2
>            Reporter: Ben Sherman
>         Attachments: fail3.log, fail5.log
>
>
> We have a 5 node cluster running 3.4.10 we saw this in .8 and .9 as well), and sometimes, a node gets a read timeout, drops all the connections and tries to re-establish itself to the quorum.  It can usually do this in a few seconds, but last night it took almost 15 minutes to reconnect.
> These are 5 servers in AWS, and we've tried tuning the timeouts, but the are exceeding any reasonable timeout and still failing.
> In the attached logs, 5 is a follower, 3 is the leader.  5 loses connectivity at 11:21:34.  3 sees the disconnect at the same moment.
> 5 tries to re-establish the quorum, but cannot do it until the connections to the other servers expire at 11:37:02.  After the connections are re-established, 5 connects immediately.
> At 11:41:08, the operator restarted the server, and it reconnected normally.
> I suspect there is a problem with stale connections to the rest of the quorum - the other services on this box were fine (monitoring, puppet) and able to establish new connections with no problems.
> I posed this problem to the zookeeper-users list and was asked to open a ticket.



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